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RoHo

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About RoHo

  • Rank
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  • Birthday 03/18/1964

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  • Location
    Vic
  • Country
    Australia
  • First Name
    Rod
  1. It's the cathodes that are connected to G3, no problem there. 1k resistors are grid-stoppers, should be located close to the grid 1 pin. They prevent oscillation. You're right about the bias being "non-adjustable, fixed bias" shared between the 2 output tubes. Cheap and nasty IMO. There is no way to correctly bias a different type of output tube which may cause BIG problems.
  2. Almost certainly the "odd" tube is shared between channels: two triode gain stages, one for Left and one for Right. Then on to separate tubes for driver/phase inverter duties.
  3. Sounds like an impedance matching issue. Passive pre-amps are very system dependent. Results can vary wildly due to the sensitivity to cable type/length and power amp input impedance.
  4. Neil Young at Foodland

    NY would probably puke if he knew his music was oozing thru the supermarket. Remember "This Notes For You" ? - "Aint singing for Pepsi/Aint singing for Coke/Aint singing for no-one/Makes my music a joke" No respect
  5. It all depends on how much the visual aesthetic bothers you. I don't need a certain style happening but I do need the room to be reasonably neat, I just can't relax and enjoy in a messy room or even a room with too much "stuff" in it. As I said, very personal, but still a genuine issue.
  6. Well.... my experience of exactly one CD player is: My Cd player is a Rotel RSD991, a very well specified and built thing, apart from the generic op-amp output stage. The DACS are PCM 63, current output types. So I disconnected the output stage, put in a simple resistor as the current to voltage converter (I/V) followed by my DIY valve pre-amp for gain. Sounded better, so it stayed that way for a few years. Then I read here and and on DIYaudio of "Lightspeed" George's experience with the AD844 chip used stacked and without feedback (thanks George). Sounded interesting and was simple to implement so I gave it a go. Immediately a more dynamic sound with a larger soundstage, so it has stayed like this since IMO it's all about the design and implementation, tubes or SS. And to do it well with tubes is not simple or cheap.
  7. A frustration of mine is that there are different types of DAC chips with different output stage requirements that can be implemented well or badly by tubes or SS. But we lump them all in either the "tube" camp or the solid-state camp. I repeat myself, and I'm willing to be contradicted, that the typical "tube" CD player, which is probably Chinese, has a delta-sigma DAC that incorporates an op-amp and doesn't really need any further processing. But it will have a chain of op-amps and a tube in there somewhere. Like 12AX7 which has very gain and is useless as an output driver. It's quite reasonable to presume that the tube is there to add "tone" ie pleasant distortion. This is a totally different situation to a current-output DAC with maybe a high quality transformer doing the current-to-voltage conversion and a more sophisticated exclusively tube, gain/output stage. A proper "tube CD player". But this is expensive and so is only found in much more expensive players.
  8. I'd want to know how the tube is implemented in the output stage. From what I've seen/heard in most "tube" CD players there are still op-amps in there doing the main job. For example a 12AX7 just can't properly do one of the tasks required - provide a low output impedance.
  9. I have to enlist the help of one of my daughters to lift my DIY amps power supply. Not good for the self-esteem
  10. Almost all "tube" CD players use the tube as a marketing device or in a basic add-on implementation IMO ( AMR would be a notable, but very expensive, exception.) Not worthy of partnering with one of Earle's creations. Put the money towards speakers. PS I really like the green transformers. PPS Use the wait-time doing back-strengthening exercises. Transformers of this capability are HEAVY
  11. Spend less on the CD and more on the speakers. Proac Tablette is renowned for being nice with valves. In your room a smaller speaker with sensitivity of about 88dB + will work fine, the above mentioned Heybrook also look ideal. I liked my previous standmount B&W CDM1's with a 20W valve amp - tamed the bright treble and detail in the midrange was excellent.. No low bass but in your room with your budget you have two choices: no bass or bad bass I know which I prefer. If your not concerned about brand names then a DIY single-driver speaker would also do a fine job. Sealed, bass reflex or back loaded horn. You see them come up for sale every so often, Earle may know of some.
  12. And now I've noticed that many items are "On Sale!" eg original price $3.28, crossed out and replaced, in red, with $33.55. Again in red, "YOU SAVE -1124% !!" I've never saved -1000% before. Should I go for it ??
  13. Which seems to point to rsknr.xyz being dodgy. Then you search for info on Scamadviser and find that it's far from squeaky clean itself - casting aspersions where none are warranted in order to undermine legit businesses. I'm very confused.
  14. Hi all, I've been browsing for a suitable aluminium enclosure for a pre-amp project. There's dozen's available on ebay and Aliexpress, the one I like most is available from a few sources at $150-200 landed in Oz. As you do I was searching by the part number for every possible seller and came across the same item on an sales site called rsknr "dot" xyz. The site calls itself a seller of fine luxury goods and whatever. The sellers name is the same as on eBay. The interesting thing is the item is WAY cheaper, like $50 included shipping according to the price calculator. So...is it legit, dodgy or just some weirdo non-functional thing?
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